Soil evaporation based on infrared thermal imaging technology

Evaporation is one of the major approaches of interaction between soil and atmosphere. Additionally, it is also an important factor which significantly controls the moisture field of soil and successively affects its engineering characteristics. In this investigation, the infrared thermal imaging technology is used to conduct experimental researches on the soil evaporation process. Three sets of soil samples with different layer thicknesses and initial moisture contents are configured. The samples are dried under the constant temperature and relative humidity conditions while their mass changes are regularly recorded to obtain the evaporation process. The temperature field of the soil surface is simultaneously monitored in real time with an infrared thermal imager. The experimental results show that the evaporation process of soil samples can be divided into three typical stages: the constant rate stage, the falling rate stage and the residual stage. In response, the soil surface temperature also undergoes three typical stages: the constant low temperature stage, the rising temperature stage and the stable stage, which correspond to the three evaporation stages. Based on the law of conservation of energy, a linear relationship between the soil evaporation rate and the temperature difference between the soil surface and the atmosphere is established through theoretical deduction and verified through experimental inspection. This relationship is found to be not affected by the initial layer thickness or moisture content of the soil samples. The research results show that it is feasible to utilize the infrared thermal imaging technology in soil evaporation studies, which provides an original approach for grasping the temporal and spatial evolution characteristics of the surface moisture field under climatic impact in a more rapid way.